1. Technical Field
An aspect of the present invention relates to an image forming apparatus with an endless belt to form an image on a recording medium. More specifically, the present invention relates to an image forming apparatus having electrostatic latent image carriers, developer devices to form an image on a recording medium in cooperation with an endless belt, and a cleaning roller to clean the endless belt.
2. Related Art
An image forming apparatus having a plurality of electrostatic latent image carriers, each of which is provided for one of a plurality of different colors usable in the image forming apparatus, developer devices provided for the electrostatic latent image carriers respectively, and an endless belt to be driven in cooperation with the electrostatic latent image carriers has been known. In the known image forming apparatus, the electrostatic latent image carriers are driven to have electrostatic latent images formed on surfaces thereof. The developer devices provide adhesive developer agent to the electrostatic latent image formed on the surfaces of the electrostatic latent image carriers so that the latent image is developed to appear on the surfaces of the electrostatic image carriers. Meanwhile, the endless belt is driven to roll in a position opposed to the electrostatic latent image carriers and serves in cooperation with the electrostatic latent image carriers and the developer devices to transfer the developer agent on the electrostatic latent image carriers to a surface of the recording medium. When the image in multiple colors is formed on a same recording medium, the electrostatic latent image is formed on the surface of corresponding electrostatic latent image carrier for each color, and the developer device corresponding to the color provides the corresponding-colored developer agent (e.g., toner) to the electrostatic latent image.
The endless belt may be designed such that, for example, the developer agents adhered to the electrostatic latent image carriers are transferred onto a surface of the endless belt to be further transferred onto a surface of the recording medium. For another example, the recording sheet may be carried on the endless belt to have the developer agent on the electrostatic latent image carriers transferred onto its surface as the endless belt rolls.
When the developer agents in four colors (e.g., black, yellow, magenta, and cyan) are used in the image forming apparatus, four pairs of electrostatic latent image carrier and developer device for the four colors are required. However, driving the four pairs of electrostatic latent image carries and developer devices separately by separate motors may be disadvantageous in terms of, for example, manufacturing cost and downsizing the image forming apparatus. Meanwhile, the image forming apparatus may be used to form the image solely in the black (monochrome) developer agent, and the other pairs of electrostatic latent image carriers and the developer devices for yellow, magenta, and cyan (colored) developer agents may standby unused. In order to overcome such inefficiency, an image forming apparatus having a motor to collectively drive the developer devices for the colored developer agents and a motor to separately drive the developer device for the black developer agent is suggested.